Add gpu::MailboxHolder to hold state for a gpu::Mailbox

content/common/gpu/client/gl_helper.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_COMMON_GPU_CLIENT_GL_HELPER_H_
 #define CONTENT_COMMON_GPU_CLIENT_GL_HELPER_H_
 
 #include "base/atomicops.h"
 #include "base/basictypes.h"
 #include "base/callback.h"
@@ skipping 278 matching lines @@
   // Simply creates a texture.
   blink::WebGLId CreateTexture();
   // Deletes a texture.
   void DeleteTexture(blink::WebGLId texture_id);
 
   // Insert a sync point into the GL command buffer.
   uint32 InsertSyncPoint();
   // Wait for the sync point before executing further GL commands.
   void WaitSyncPoint(uint32 sync_point);
 
-  // Creates a mailbox that is attached to the given texture id, and a sync
-  // point to wait on before using the mailbox. Returns an empty mailbox on
-  // failure.
+  // Creates a mailbox holder that is attached to the given texture id, with a
+  // sync point to wait on before using the mailbox. Returns a holder with an
+  // empty mailbox on failure.
   // Note the texture is assumed to be GL_TEXTURE_2D.
-  gpu::Mailbox ProduceMailboxFromTexture(blink::WebGLId texture_id,
-                                         uint32* sync_point);
+  gpu::MailboxHolder ProduceMailboxHolderFromTexture(blink::WebGLId texture_id);
 
   // Creates a texture and consumes a mailbox into it. Returns 0 on failure.
   // Note the mailbox is assumed to be GL_TEXTURE_2D.
   blink::WebGLId ConsumeMailboxToTexture(const gpu::Mailbox& mailbox,
                                           uint32 sync_point);
 
   // Resizes the texture's size to |size|.
   void ResizeTexture(blink::WebGLId texture, const gfx::Size& size);
 
   // Copies the framebuffer data given in |rect| to |texture|.
@@ skipping 86 matching lines @@
       const gpu::Mailbox& mailbox,
       uint32 sync_point,
       const scoped_refptr<media::VideoFrame>& target,
       const base::Callback<void(bool)>& callback) = 0;
   virtual GLHelper::ScalerInterface* scaler() = 0;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_GPU_CLIENT_GL_HELPER_H_